Summary of Work: Historically, research on genetic and environmental factors affecting reproduction and subsequent development of the offspring has been centered on the female. After a year-long assessment of the world literature, however, the need for an epidemiologic study of male-mediated reproductive outcomes was clear. Therefore we have obtained data from the European Longitudinal Study of Pregnancy and Childhood being conducted at Bristol, England ("ALSPAC"). In the ALSPAC study, more than 7,000 partners of women who delivered infants in Avon County, England during 1991-2 provided lifetime occupational and toxic exposure histories. The infants and their parents will be followed for seven years. We have coded occupational histories of both mothers and father, using the British Standard Occupational Codes, and categorized the self-reported exposures on the job and in the home. We are focusing now on the mothers. One paper has been accepted showing significant differences in fetal growth, between trade/craft occupations and professional occupations. Another is in progress showing decreased fetal growth among mothers employed in the printing trades.